JPS60195866A - Flat cell - Google Patents

Abstract

PURPOSE:To resolve a short-circuit through an equipment side spring terminal at the through hole portion exposing the terminal by covering and shielding an aluminum foil exposed portion with resin films at the inner periphery of the through hole for exposing the terminal provided at one portion of the outer film of a multi-layer structure. CONSTITUTION:At the through hole 10 portion for exposing a terminal formed on the outer film of a multi-layer structure, the end surface of an aluminum foil 2 at the middle of the outer film is covered and shielded with upper and lower resin films 1, 3 so as not to be exposed at all. The through hole portion of the outer film is formed by boring the through hole on the outer film then melting the end face section of the aluminum foil 2 on the inner periphery of the through hole of the outer film by chemical treatment such as etching. Then, the resin film 1 and resin film 3 are united 15 in one body under heat and pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a flat electricity generating element in which a flat power generation element is sealed by a multilayered exterior film mainly composed of a resin film and having a thin metal film such as aluminum foil in the middle. This relates to improvements in batteries.

Conventional configuration and its problems Conventionally, the exterior film of a flat battery, in which a flat power generating element is sealed with a multilayered exterior film mainly made of resin film, has been designed to prevent the electrolyte from permeating and dissipating.
In addition, in order to provide mechanical strength to the exterior film, thinly rolled aluminum foil is placed as one layer within the exterior film. A through hole is provided in a portion of the exterior film, and the terminal board is exposed through the through hole.

It is used as a negative terminal.

FIG. 1 is an enlarged sectional view showing a typical structure of a flat battery. In the figure, the power generation element of the battery is sealed with an exterior film a in which resin films 1 and 3 are laminated on both upper and lower surfaces of an aluminum foil 2.

A positive electrode layer 5 and a negative electrode layer 7 mainly composed of active materials are provided on both sides of a separator 6 containing an electrolytic solution, and a positive electrode terminal plate 4 and a negative electrode terminal plate 8 are provided on the outside thereof.

The positive electrode terminal plate 4 and the exterior film a are heat-welded.

Around the battery, exterior films a are adhered 9 to each other to make it liquid-tight. The battery output is taken out from the terminal plate 4.8 extending a into the through hole 10.1j of the exterior film d.

The outer layer 1 of the resin used for the exterior film is often made of polyester, nylon, vinylon, polyethylene, etc.
The inner layer 3 is made of modified polyethylene.

tJl polypropylene, ionomer resin, EAA resin, EVA resin, etc. are used.

However, with such a structure, there is a risk of a short circuit occurring when the battery loaded in the device is used.

For example, when the exposed end portion 1θ of the aluminum foil 2 on the inner circumferential surface of the through-holes 1Q and 11 in the exterior film comes into contact with the terminal plate on the device side and the positive terminal plate 4, the aluminum foil 2 in the exterior film is passed through. Further, from the exposed part 12 of the aluminum foil 2 around the exterior film, through the conductive battery case, through the exposed part 13 of the aluminum foil 2, and through the aluminum foil 2 in the exterior film, it reaches the negative terminal plate 8. Creates a short circuit. In addition, the terminal plates 4 and 8 and the aluminum foil 2 in the exterior film are sandwiched with a resin film 3,
Although they are separated, their thickness is approximately 30 μm to 100 μm, and as described above, depending on the direction of punching, the aluminum foil and the terminal plate can easily come into contact with each other. Two methods were considered to prevent this. These are shown in Figure 2.
It is shown in Figure 3.

In Fig. 2, contact between the terminal plate 4 and the aluminum foil 2 is prevented by making the inner diameter of the through hole in the resin film 3 constituting the exterior film smaller than that of the resin film 1 and aluminum foil 2 located on the outside. be. As shown in FIG. 2, the wedge terminal 14 (indicated by a broken line) acts as a bridge between the terminal plate 4 and the aluminum foil 2, and there is a risk of short circuit.

Another example is shown in FIG. This is to prevent a short circuit between the aluminum foil 2 and the terminal plate 4 by making the inner diameter of the through hole in the aluminum foil 2, which is a conductor, larger than that of the resin film 1.3.0However, this structure also prevents short circuits between the aluminum foil 2 and the terminal plate 4. When loading and unloading, there is a risk that the resin film 1 may be torn or rolled up due to the terminal 14, and as a result, the second
Similar to the structure shown in the figure, the spring terminal 14 served to connect the terminal plate 4 and the aluminum foil 2, causing a short circuit.

OBJECTS OF THE INVENTION The present invention solves these conventional problems and eliminates short circuits caused by device-side spring terminals at the through-hole portions where the terminals are exposed.

Structure of the Invention - In order to achieve the object described in F, the exposed part of the aluminum foil is covered and concealed with a resin film at the inner periphery of the through hole for exposing the terminal provided in a part of the exterior film of the multilayer structure, The cut edges of the aluminum foil are not exposed at all in the perforated area.

Description of examples The details of the present invention will be explained below using examples.

Figure 4 shows a multilayered exterior film. In the through hole 1o formed in this film for terminal exposure, the end face of the aluminum foil 2 in the middle of the exterior film is completely exposed by the resin films 1 and 3 above and below it. It is covered and hidden to prevent it from being exposed.

The formation of the perforated portion of the exterior film in the present invention is as follows:
After making a hole in the exterior film, the aluminum foil 2 on the inner circumferential surface of the hole in the exterior film is removed by chemical treatment such as etching.
Dissolve the end face of. Thereafter, the resin film 1 and the resin film 3 may be integrated 16 by heating and Calo pressure. The resin films 1.3 may be made of the same material or may be made of different materials.

Effects of the Invention A flat battery using an exterior film produced as described above has a structure in which the aluminum foil is completely insulated even if the terminal on the device side contacts the inner circumferential surface of the through hole in the exterior film. Since it is covered and hidden with a resin film, short circuits through the aluminum foil can be completely prevented.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a typical structure of a flat battery, FIGS. 2 and 3 are cross-sectional views showing conventional examples of through-holes in an exterior film, and FIG. 4 is an exterior film according to an embodiment of the present invention. Oa is a cross-sectional view showing the through-hole portion of the exterior film, 1
．． 3...Resin film, 2...Aluminum foil, 10...Through hole in exterior film, 16
...Resin that covers and hides the cut edges of aluminum foil.

Claims (1)

[Claims] A battery in which a flat power generation element consisting of positive and negative electrode active materials, terminal plates for both positive and negative electrodes, and a separator is covered with an exterior film that has an aluminum foil in the middle part of the resin film, and a part of the terminal plate is 1. A flat battery characterized in that an exposed portion of an aluminum foil placed in the middle of an exterior resin film around a through hole provided in the exterior film so as to be exposed is covered and concealed with a resin film.